Numerous processes are known for the separation of air by cryogenic distillation into its constituent components, representative among these are U.S. Pat. Nos. 3,729,493; 4,533,375; 4,578,095; 4,604,116; 4,605,427 and 4,670,031.
In addition, examples of structured or ordered packings are known in the art, representative among these are U.S. Pat. Nos. 4,128,684; 4,186,159; 4,296,050; 4,455,339; 4,497,751; 4,497,752 and 4,497,753.